Vagotomy inhibits the jejunal fluid secretion activated by luminal ileal Escherichia coli STa in the rat in vivo

Background-Escherichia coil heat stable enterotoxin (STa) is a major cause of secretory diarrhoea in humans. Aims-To assess the effects of instilling STa into the ileum on remote fluid secretion in the jejunum and colon in rats in vivo by a gravimetric techni que. Methods and results-Ileal STa (55 ng/ml) stimulated fluid secretion in both heal and jejunal loops but not in the colon. The fluid secretion induced b y heal STa was inhibited by L-NAME (N-omega-nitro-L-arginine methyl ester, 40 mg/kg intraperitoneally) but not by D-NAME (N-omega-nitro-D-arginine met hyl ester). Ileal carbachol (183 mg/ml) instilled into the lumen stimulated ileal secretion but not jejunal secretion, and was unaffected by L-NAME. C apsaicin (10 mu M), instilled luminally with STa in the ileum, blocked both the ileal and jejunal fluid secretion. Acute bilateral vagotomy prevented luminal ileal STa from inducing jejunal fluid secretion but not from activa ting ileal fluid secretion. Conclusion-Ileal E coil STa stimulates remote secretion in the rat jejunum but not in the colon, probably by a nitrinergic, vagal reflex mediated by C fibres. This neural pathway will amplify the action of the toxin in its ge neration of secretory diarrhoea.